WO2014184880A1

WO2014184880A1 - Aluminum alloy material, single layer of which allows thermal bonding; manufacturing method therefor; and aluminum bonded body using said aluminum alloy material

Info

Publication number: WO2014184880A1
Application number: PCT/JP2013/063454
Authority: WO
Inventors: 黒崎友仁; 新倉昭男; 寺山和子; 村瀬崇; 松居悠; 望月淳一; 荒木俊雄
Original assignee: 株式会社Uacj
Priority date: 2013-05-14
Filing date: 2013-05-14
Publication date: 2014-11-20
Also published as: BR112015028766B1; CN105229182A; EP2998412B1; KR20160009600A; BR112015028766A2; US20160089860A1; JP5732594B2; EP2998412A4; EP2998412A1; MX2015015592A; JPWO2014184880A1; CN105229182B; KR102118856B1

Abstract

This invention provides the following: an aluminum alloy material, a single layer of which allows thermal bonding without the use of a bonding member such as a brazing or welding filler metal; a method for bonding said aluminum alloy material; and an aluminum bonded body using said aluminum alloy material. This invention provides an aluminum alloy material that is characterized by comprising an aluminum alloy that contains silicon in the amount of 1.0-5.0 mass% and iron in the amount of 0.01-2.0 mass%, with the remainder comprising aluminum and unavoidable impurities. Said aluminum alloy material is also characterized in that 10 to 1×10⁴ aluminum-based intermetallics having equivalent circular diameters of 0.01-0.5 µm are present per cubic micrometer and no more than 200 silicon-based intermetallics having equivalent circular diameters of 5.0-10 µm are present per cubic millimeter. This invention also provides the following: a method for manufacturing said aluminum alloy material; and an aluminum bonded body using said aluminum alloy material.

Description

Aluminum alloy material having heat bonding function in a single layer, manufacturing method thereof, and aluminum joined body using the aluminum alloy material

The present invention heats the other members in a single layer by supplying a liquid phase necessary for joining without using a joining member such as a brazing material or a filler material and the material itself is in a semi-molten state. Aluminum alloy material that can be joined and joining method thereof, and aluminum joined body using the aluminum material, and more specifically, an aluminum alloy material that can be heat joined in a single layer excellent in deformation resistance during joining heating, and its The present invention relates to a joining method and an aluminum joined body using the aluminum material.

In manufacturing a structure such as a heat exchanger having an aluminum alloy material as a constituent member, it is necessary to join aluminum alloy materials together or an aluminum alloy material and a different material. Various methods are known for joining aluminum alloy materials, and brazing methods (brazing methods) are often used among them. The brazing method is often used because it takes into account advantages such as being able to obtain a strong bond in a short time without melting the base material. Examples of a method for producing a heat exchanger using a joining method of an aluminum alloy material by a brazing method include a method using a brazing sheet clad with a brazing material made of an Al—Si alloy; an extruded material coated with a powder brazing material And a method in which a brazing material is separately applied to a portion that needs to be joined after assembling each material (Patent Documents 1 to 3). Furthermore, the section of “3.2 Brazing sheet” in Non-Patent Document 1 describes details of these clad brazing sheets and powder brazing materials.

So far, various brazing methods have been developed in the manufacture of aluminum alloy structural bodies. For example, in a heat exchanger for automobiles, when a fin material is used in a single layer, a method of using a brazing sheet in which a tube material is clad with a brazing material, or a method of separately applying Si powder or Si-containing wax to the tube material Was adopted. On the other hand, when the tube material is used as a single layer, a method of using a brazing sheet in which a fin material is clad with a brazing material has been adopted.

Patent Document 4 describes a method using a single-layer brazing sheet instead of the clad brazing sheet described above. In this method, it has been proposed to use a single layer brazing sheet for a heat exchanger for the tube material and the tank material of the heat exchanger. Here, an aluminum alloy material called a single-layer brazing sheet and used in the MONOBRAZE method is referred to as an aluminum alloy material having a single-layer heat bonding function in the present invention.

In Patent Document 5, in a method of manufacturing a joined body using a single-layer aluminum alloy material, by controlling the alloy composition, temperature during joining, pressurization, surface properties, etc., it is possible to obtain a good joint and deform. There has been proposed a joining method in which almost no occurrence occurs. In the present invention, the joining method disclosed in Patent Document 5 is called a MONOBRAZE method.

Patent Document 6 discloses a structure in which a single layer aluminum alloy is used as a tube material, and a good bondability is obtained by controlling the size of dispersed particles in the tube material when a heat exchanger is manufactured by the MONOBRAZE method. Has been proposed.

JP 2008-303405 A JP 2009-161835 A JP 2008-308760 A JP 2010-168613 A Japanese Patent No. 5021097 JP 2012-51028 A

In order to produce a clad material such as a brazing sheet, it is necessary to produce each layer separately and further to laminate them. The use of a brazing sheet is against the demand for cost reduction of heat exchangers and the like. Also, the application of the powder brazing material is reflected in the product cost by the amount of the brazing material cost.

On the other hand, as described above, there is also a proposal to apply an aluminum alloy material having a heat bonding function with a single layer instead of a brazing sheet made of a clad material. In this method, it has been proposed to maintain the shape as a structure while supplying a liquid phase necessary for bonding from an aluminum alloy material having a heat bonding function with a single layer. However, for example, in the production of a heat exchanger, if an aluminum alloy material having a heat bonding function with a single layer is used as it is as a tube material or a fin material, there is a possibility that it will be greatly deformed by heating during the production of the heat exchanger.

In addition, as in the above-described MONOBRAZE method, by controlling the alloy composition, bonding temperature, pressure, surface properties, etc., even in bonding using an aluminum alloy material having a single-layer heating bonding function, it is good A method for achieving both joining and shape maintenance has also been proposed. However, it is desired to achieve higher precision bonding and shape maintenance during bonding. In particular, a fin material having a plate thickness of 1 mm or less is likely to be deformed by bending stress in the plate thickness direction, and the liquid phase ratio needs to be kept low in order to maintain the shape during bonding. However, since the volume of the material is small, it is difficult to sufficiently generate a liquid phase at a low liquid phase ratio, and further improvement has been demanded to achieve both bonding and shape maintenance.

As described above, in order to reduce the cost of an aluminum alloy structure such as a heat exchanger, it can be said that the MONOBRAZE method in which bonding is performed using a single-layer material without using a brazing material is preferable. However, it is difficult to avoid the problem of deformation of the member or a decrease in the bonding rate even if an aluminum alloy material having a heat bonding function with a single layer is simply applied to the MONOBRAZE method. In the above-mentioned

Patent Documents

4 and 6, the deformation is not significant by applying a single-layer aluminum alloy material to a tube material having a relatively thick plate thickness. In the case of applying an aluminum alloy material, there has been a problem that the deformation during bonding heating is significant.

The present invention has been made based on the background as described above. When manufacturing various aluminum alloy joined bodies using a single-layer aluminum alloy material by the MONOBRAZE method, the temperature of the solidus is higher than the solidus temperature at the time of joining heating. A single-layer aluminum alloy material excellent in deformation resistance and a joining method thereof, and an aluminum joined body using the aluminum alloy material It is what we propose. In particular, the present invention is suitable for a thin material such as a fin material for a heat exchanger.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have improved the aluminum alloy material used in the MONOBRAZE method, so that it is heated to a temperature higher than the solidus temperature at the time of bonding heating and becomes a semi-molten state. First, the present inventors have found that an aluminum alloy material excellent in deformation resistance during bonding heating has been obtained, and the present invention has been completed.

That is, the aluminum alloy material according to the present invention is made of an aluminum alloy containing Si: 1.0 to 5.0 mass%, Fe: 0.01 to 2.0 mass%, the balance being Al and inevitable impurities, Al system intermetallic compound having an equivalent circle diameter of .01 ~ 0.5 [mu] m is 10 ~ 1 × 10 ⁴ cells / [mu] m ³ exists, Si-based intermetallic compound having an equivalent circle diameter of 5.0 ~ 10 [mu] m is 200 An aluminum alloy material having a heat bonding function with a single layer characterized by the presence of / mm ² or less.

The amount of solute Si contained in the aluminum alloy is 0.7% or less.

The aluminum alloy further contains one or more selected from Mg: 0.05 to 2.0 mass%, Cu: 0.05 to 1.5 mass%, and Mn: 0.05 to 2.0 mass%. You should do it.

The aluminum alloy may further contain one or more selected from Zn: 6.0 mass% or less, In: 0.3 mass% or less, and Sn: 0.3 mass% or less.

The aluminum alloy is selected from Ti: 0.3 mass% or less, V: 0.3 mass% or less, Cr: 0.3 mass% or less, Ni: 2.0 mass% or less, and Zr: 0.3 mass% or less. Or it is good to further contain 2 or more types.

The aluminum alloy is one selected from Be: 0.1 mass% or less, Sr: 0.1 mass% or less, Bi: 0.1 mass% or less, Na: 0.1 mass% or less, and Ca: 0.05 mass% or less. Or it is good to further contain 2 or more types.

The aluminum alloy has a tensile strength of 80 to 250 MPa before heat bonding.

The present invention is also a method for producing an aluminum alloy material having a heat bonding function with a single layer as described above, wherein the aluminum alloy for the aluminum alloy material is continuously rolled and rolled, and a rolled plate is cooled. Including two or more cold rolling processes for hot rolling and an annealing process for annealing the rolled sheet one or more times during the cold rolling process. The annealing conditions in all annealing processes are 1 to 2 at a temperature of 250 to 550 ° C. It includes a method for producing an aluminum alloy material having a single layer and a heat bonding function, characterized in that it is 10 hours and the rolling reduction in the final cold rolling stage is 50% or less.

In the twin roll type continuous casting and rolling in the casting process, a rolled plate having a thickness of 1 to 500 μm mainly composed of aluminum and aluminum oxide is rolled in a state of adhering to the surface of the twin roll, and the rolling plate width is about 1 mm. It is assumed that the rolling load is 500 to 5000 N.

The present invention further provides an aluminum joined body manufactured by heat-joining two or more aluminum members, and using the aluminum alloy material described above for at least one of the two or more aluminum members. Including.

After the heat bonding, the crystal grain size in the metal structure of the aluminum alloy material used for at least one of the two or more members is 100 μm or more.

The aluminum alloy material according to the present invention has a heat bonding function with a single layer unlike conventional bonding methods such as brazing, and can be bonded to various members to be bonded in a single layer state. And although it will be in a semi-molten state at the time of joining heating, it is an aluminum material excellent in deformation resistance. Thereby, the request | requirement of the cost reduction in manufacture of a conjugate | zygote can be answered. For example, it is useful as a material having a very thin plate thickness, such as a heat exchanger fin material. In addition, it can be applied to products that require higher precision bonding and dimensional systems. Further, it is possible to manufacture a joined body having a shape that is impossible with the conventional joining method and to reduce the thickness of the member.

It is explanatory drawing for demonstrating the cooling rate of the inject | poured molten aluminum in the twin roll type continuous casting rolling method. It is explanatory drawing for demonstrating the cooling rate of the inject | poured molten aluminum in the twin roll type continuous casting rolling method. FIG. 4 is an external view of a three-stage test piece (minicore) used in the first to third embodiments.

1. Hereinafter, the present invention will be described in detail. First, an aluminum alloy material having a heat bonding function with a single layer according to the present invention will be described. This aluminum alloy material contains, as essential elements, Si concentration: 1.0 to 5.0 mass% (hereinafter, simply referred to as “%”) and Fe: 0.01 to 2.0%, the balance being Al and inevitable An Al—Si—Fe-based aluminum alloy composed of impurities has a basic composition, and an Al-based intermetallic compound having a circle-equivalent diameter of 0.01 to 0.5 μm exists in the metal structure. Hereinafter, these features will be described.

1-1. About essential elements 1-1-1. Regarding Si Concentration Regarding Si concentration, Si is an element that generates an Al—Si-based liquid phase and contributes to bonding. However, when the Si concentration is less than 1.0%, a sufficient amount of liquid phase cannot be generated, the liquid phase oozes out and bonding becomes incomplete. On the other hand, if it exceeds 5.0%, the amount of liquid phase generated in the aluminum alloy material increases, so that the material strength during heating is extremely reduced, and it becomes difficult to maintain the shape of the structure. Therefore, the Si concentration is defined as 1.0% to 5.0%. The Si concentration is preferably 1.5% to 3.5%, more preferably 2.0% to 3.0%. Since the amount of the liquid phase that oozes out increases as the volume increases and the heating temperature increases, the amount of the liquid phase required during heating depends on the amount of Si required for the structure of the structure to be manufactured and the bonding heating. It is desirable to adjust the temperature.

1-1-2. Regarding Fe Concentration Regarding Fe concentration, Fe has the effect of improving the strength by being slightly dissolved in the matrix, and also has the effect of preventing the strength from being lowered particularly at high temperatures by being dispersed as a crystallized product or a precipitate. . When the addition amount of Fe is less than 0.01%, not only the above effect is small, but also high purity metal must be used and the cost increases. On the other hand, if it exceeds 2.0%, a coarse intermetallic compound is produced at the time of casting, causing a problem in manufacturability. Further, when the joined body is exposed to a corrosive environment (particularly a corrosive environment in which a liquid flows), the corrosion resistance decreases. Furthermore, since the crystal grains recrystallized by heating at the time of bonding are refined and the grain boundary density increases, the dimensional change increases before and after the bonding. Therefore, the addition amount of Fe is set to 0.01% to 2.0%. A preferable addition amount of Fe is 0.2% to 1.0%.

1-2. Next, the characteristics of the metal structure of the aluminum alloy material according to the present invention will be described. The aluminum alloy material according to the present invention is heated to the solidus temperature or higher during bonding heating by the MONOBRAZE method. At this time, the aluminum alloy material is deformed mainly by grain boundary sliding. Therefore, as the metal structure, (1) it is desirable that the crystal grains become coarse during bonding heating. (2) Further, when a liquid phase is generated at the grain boundary, deformation due to the grain boundary slip is likely to occur, so that it is desirable to suppress generation of the liquid phase at the grain boundary. In the present invention, the crystal structure after heating becomes coarse, and the metal structure in which the liquid phase generation at the grain boundary is suppressed is defined.

That is, in the aluminum alloy material having a heat bonding function with a single layer according to the present invention, an Al-based intermetallic compound having an equivalent circle diameter of 0.01 to 0.5 μm exists as dispersed particles. This Al-based intermetallic compound is composed of Al-Fe-based, Al-Fe-Si-based, Al-Mn-Si-based, Al-Fe-Mn-based, Al-Fe-Mn-Si-based compounds, etc. It is an intermetallic compound to be formed. An Al-based intermetallic compound having a circle-equivalent diameter of 0.01 to 0.5 μm does not become a recrystallization nucleus when heated, but functions as pinning particles that suppress the growth of grain boundaries. Moreover, it becomes a nucleus which a liquid phase produces | generates and has a function which collects the solid solution Si in a grain. Since the aluminum alloy material according to the present invention has an Al-based intermetallic compound having an equivalent circle diameter of 0.01 to 0.5 μm, the recrystallization nuclei are prevented from growing innumerably during heating, and the limited recrystallization nuclei. Since only the crystal grows, the crystal grains after heating become coarse. Further, by collecting solid solution Si in the grains, liquid phase generation at the grain boundaries is relatively suppressed.

1-2-1. About the volume density of Al type intermetallic compound The effect of said Al type intermetallic compound is more reliably exhibited because the volume density of Al type intermetallic compound is an appropriate range. Specifically, it exists at a volume density of 10 to 1 × 10 ⁴ pieces / μm ³ in any part of the material. When the volume density is less than 10 particles / μm ³ , the pinning effect is too small, so that the number of recrystallized grains that can be grown increases and coarse crystal grains are hardly formed. In addition, since the nuclei for liquid phase generation are reduced, the action of collecting the solid solution Si within the grains is not sufficiently exerted, and the ratio of the solid solution Si within the grains contributing to the growth of the liquid phase generated at the grain boundaries increases. In addition, the deformation resistance is reduced. On the other hand, when the volume density exceeds 1 × 10 ⁴ particles / μm ³ , since the pinning effect is too great, the growth of all recrystallized grains is suppressed and coarse crystal grains are hardly formed. Moreover, since there are too many nuclei of liquid phase production | generation, the liquid phase which touches a grain boundary directly will increase, and the liquid phase of a grain boundary will grow more. Due to the pinning effect of appropriate strength, only limited crystal grains grow and the grains become coarse, and form appropriate liquid phase nuclei, collect solid solution Si in the grains and collect the grains In order to suppress generation of a liquid phase at the boundary, the volume density is within the above range. The volume density is preferably 50 to 5 × 10 ³ pieces / μm ² , and more preferably 100 to 1 × 10 ³ pieces / μm ² .

1-2-2. Regarding the equivalent circle diameter of Al-based intermetallic compounds Al-based intermetallic compounds having an equivalent circle diameter of less than 0.01 μm are excluded because they are substantially difficult to measure. In addition, although Al-based intermetallic compounds having an equivalent circle diameter of more than 0.5 μm exist, they do not act effectively as pinning particles, so the effects according to the present invention are small and are not regulated. An Al-based intermetallic compound having an equivalent circle diameter of more than 0.5 μm can act as a nucleus for liquid phase formation. However, since the effect of collecting solute Si in the grains is determined by the distance from the compound surface, an Al-based intermetallic compound having an equivalent circle diameter exceeding 0.5 μm reduces the effect of collecting solute Si per volume of the compound. Also excluded from the scope.

Note that the equivalent circle diameter of the Al-based intermetallic compound can be determined by TEM observation of a thin-walled sample by electrolytic polishing. Here, the equivalent circle diameter means the equivalent circle diameter. It is preferable to obtain the equivalent circle diameter before joining by analyzing the TEM observation image as a two-dimensional image in the same manner as the SEM observation image. In order to calculate the volume density, the film thickness of the sample is also measured using the EELS method or the like in each field of view observed by TEM. After image analysis of the TEM observation image as a two-dimensional image, the measurement volume is obtained by multiplying the measurement area of the two-dimensional image by the film thickness measured by the EELS method, and the volume density is calculated. If the thickness of the sample is too thick, the number of particles overlapping in the electron transmission direction increases, making accurate measurement difficult. Therefore, it is desirable to observe a portion having a thickness in the range of 50 nm to 200 nm. Si-based intermetallic compounds and Al-based intermetallic compounds can be more accurately distinguished by elemental analysis using EDS or the like.

As described above, the aluminum alloy material having a heat bonding function with a single layer according to the present invention having characteristics in the Si and Fe concentration ranges and the metal structure is in a semi-molten state to supply a liquid phase during bonding heating. This makes it possible to join and has excellent deformation resistance.

1-3. About Si type intermetallic compound In addition to the prescription | regulation regarding the said Al type intermetallic compound, in the aluminum alloy material which concerns on this invention, it prescribes | regulates also about Si type intermetallic compound. In the aluminum alloy material according to the present invention, Si-based intermetallic compounds having a circle-equivalent diameter of 5.0 to 10 μm are present in a cross section in the material of 200 pieces / mm ² or less. Here, the Si-based intermetallic compound includes (1) elemental Si, and (2) an element such as Ca or P in part of elemental Si. The cross section in the material is an arbitrary cross section of the aluminum alloy material, for example, a cross section along the thickness direction, or a cross section parallel to the plate material surface. From the viewpoint of simplicity of material evaluation, it is preferable to adopt a cross section along the thickness direction.

1-3-1. Area density of Si-based intermetallic compound Here, a Si-based intermetallic compound having a circle-equivalent diameter of 5.0 μm to 10 μm becomes a nucleus of recrystallization when heated. For this reason, when the surface density of the Si-based intermetallic compound exceeds 200 / mm ² , the crystal grains become fine because of many recrystallization nuclei, and the deformation resistance during bonding heating decreases. If the surface density of the Si-based intermetallic compound is 200 pieces / mm ² or less, since the number of recrystallized nuclei is small, only specific crystal grains grow and coarse crystal grains are obtained, which is resistant to deformation during bonding heating. Improves. The surface density is preferably 20 pieces / mm ² or less. Note that the smaller the amount of Si-based intermetallic compound having an equivalent circle diameter of 5.0 μm to 10 μm, the better the deformation resistance. Therefore, the surface density is most preferably 0 piece / mm ² .

1-3-2. Regarding the equivalent circle diameter of the Si-based intermetallic compound The equivalent circle diameter of the Si-based intermetallic compound is limited to 5.0 μm to 10 μm for the following reason. Although Si-based intermetallic compounds having an equivalent circle diameter of less than 5.0 μm exist, they were excluded from the subject because they do not work as recrystallization nuclei. In addition, Si-based intermetallic compounds having an equivalent circle diameter exceeding 10 μm cause cracks during production and are difficult to produce. Therefore, since the Si-based intermetallic compound having such a large equivalent circle diameter is not present in the aluminum alloy, it was also excluded from the object.

The equivalent circle diameter of the Si-based intermetallic compound can be determined by performing SEM observation (reflection electron image observation) of the cross section. Here, the equivalent circle diameter means the equivalent circle diameter. It is preferable to obtain the equivalent circle diameter of the dispersed particles before joining by image analysis of the SEM photograph. The surface density can be calculated from the image analysis result and the measurement area. Further, the Si-based intermetallic compound and the Al-based intermetallic compound can also be distinguished by contrast contrast by SEM-reflection electron image observation. Further, the metal species of the dispersed particles can be more accurately specified by EPMA (X-ray microanalyzer) or the like.

1-4. About the amount of Si solid solution Moreover, in the aluminum alloy material which concerns on this invention, in addition to prescription | regulation of the said Al type intermetallic compound and Si type intermetallic compound, Si solid solution amount is prescribed | regulated. The aluminum alloy material according to the present invention preferably has a Si solid solution amount of 0.7% or less before bonding by the MONOBRAZE method. The Si solid solution amount is a measured value at room temperature of 20 to 30 ° C. As described above, solute Si diffuses in the solid phase during heating and contributes to the growth of the surrounding liquid phase. If the amount of solute Si is 0.7% or less, the amount of liquid phase generated at the grain boundary due to diffusion of solute Si is reduced, and deformation during heating can be suppressed. On the other hand, when the amount of dissolved Si exceeds 0.7%, Si taken up in the liquid phase generated at the grain boundary increases. As a result, the amount of liquid phase generated at the grain boundary increases, and deformation easily occurs. A more preferable amount of solute Si is 0.6% or less. In addition, although the lower limit of the amount of solute Si is not specifically limited, it naturally depends on the Si content of the aluminum alloy and the manufacturing method, and is 0% in the present invention.

1-5. Regarding the first selective additive element As described above, a single layer aluminum alloy material having a heat bonding function according to the present invention has a predetermined amount of Si as an essential element in order to improve deformation resistance during bonding heating. And Fe. In order to further improve the strength, in addition to the essential elements Si and Fe, one or more selected from a predetermined amount of Mn, Mg and Cu are further added as the first selective additive element. Is done. Even when such a first selective additive element is contained, the volume density of the Al-based intermetallic compound and the surface density of the Si-based intermetallic compound are defined as described above.

1-5-1. About Mn Mn forms Al—Mn—Si, Al—Mn—Fe—Si, and Al—Mn—Fe intermetallic compounds together with Si and Fe, and acts as dispersion strengthening, or an aluminum matrix It is an important additive element that improves the strength by solid solution and solid solution strengthening. If the amount of Mn added exceeds 2.0%, a coarse intermetallic compound is easily formed and the corrosion resistance is lowered. On the other hand, if the amount of Mn added is less than 0.05%, the above effect is insufficient. Therefore, the amount of Mn added is 0.05 to 2.0% or less. A preferable Mn addition amount is 0.1% to 1.5%.

1-5-2. About Mg Mg undergoes age hardening by Mg ₂ Si after bonding heating, and the strength is improved by this age hardening. Thus, Mg is an additive element that exhibits the effect of improving the strength. If the amount of Mg added exceeds 2.0%, it reacts with the flux to form a high melting point compound, so that the bondability is significantly lowered. On the other hand, if the amount of Mg added is less than 0.05%, the above effect is insufficient. Therefore, the amount of Mg added is 0.05 to 2.0%. A preferable amount of Mg is 0.1% to 1.5%.

1-5-3. About Cu Cu is an additive element that improves the strength by solid solution in the matrix. When the amount of Cu added exceeds 1.5%, the corrosion resistance decreases. On the other hand, if the amount of Cu added is less than 0.05%, the above effect is insufficient. Therefore, the addition amount of Cu is set to 0.05 to 1.5%. A preferable Cu addition amount is 0.1% to 1.0%.

1-6. Second selective additive element In the present invention, in order to further improve the corrosion resistance, in addition to the essential element and / or the first selective additive element, a predetermined amount of Zn, In and Sn is selected. One kind or two or more kinds are further added as a second selective additive element. Even when such a second selective additive element is contained, the volume density of the Al-based intermetallic compound and the surface density of the Si-based intermetallic compound are defined as described above.

1-6-1. About Zn Addition of Zn is effective in improving corrosion resistance by sacrificial anticorrosive action. Zn is dissolved almost uniformly in the matrix, but when a liquid phase is generated, it dissolves into the liquid phase and concentrates in the liquid phase. When the liquid phase oozes out to the surface, the Zn concentration in the oozed portion increases, so that the corrosion resistance is improved by the sacrificial anodic action. Further, when the aluminum alloy material of the present invention is applied to a heat exchanger, the sacrificial anticorrosion action for preventing corrosion of tubes and the like can be exerted by using the aluminum alloy material of the present invention for fins. If the amount of Zn added exceeds 6.0%, the corrosion rate increases and the self-corrosion resistance decreases. Therefore, the Zn addition amount is set to 6.0% or less. A preferable Zn addition amount is 0.05% to 6.0%.

1-6-2. About Sn and In Sn and In have an effect of exerting a sacrificial anodic action. When each added amount exceeds 0.3%, the corrosion rate increases and the self-corrosion resistance decreases. Therefore, the addition amounts of Sn and In are each 0.3% or less. A preferable addition amount of Sn and In is 0.05% to 0.3%, respectively.

1-7. About the third selective additive element In the present invention, in order to further improve the strength and corrosion resistance, in addition to at least one of the essential element, the first selective additive element and the second selective additive element, One or more selected from a predetermined amount of Ti, V, Cr, Ni and Zr is further added as a third selective additive element. Even when such a third selective additive element is contained, the volume density of the Al-based intermetallic compound and the surface density of the Si-based intermetallic compound are defined as described above.

1-7-1. About Ti and V In addition to improving the strength by solid solution in the matrix, Ti and V are distributed in layers and have an effect of preventing the progress of corrosion in the thickness direction. When the added amount exceeds 0.3%, coarse crystals are generated, which impairs moldability and corrosion resistance. Therefore, the added amounts of Ti and V are each 0.3% or less. A preferable addition amount of Ti and V is 0.05% to 0.3%, respectively.

1-7-2. About Cr Cr improves the strength by solid solution strengthening and acts on coarsening of crystal grains after heating by precipitation of an Al—Cr intermetallic compound. When the addition amount exceeds 0.3%, it becomes easy to form a coarse intermetallic compound, and the plastic workability is lowered. Therefore, the addition amount of Cr is set to 0.3% or less. A preferable addition amount of Cr is 0.05% to 0.3%.

1-7-3. About Ni Ni crystallizes or precipitates as an intermetallic compound, and exhibits the effect of improving the strength after bonding by dispersion strengthening. The amount of Ni added is in the range of 2.0% or less, preferably in the range of 0.05% to 2.0%. When the Ni content exceeds 2.0%, it becomes easy to form a coarse intermetallic compound, and the workability is lowered and the self-corrosion resistance is also lowered.

1-7-4. About Zr Zr precipitates as an Al—Zr-based intermetallic compound, and exhibits the effect of improving the strength after bonding by dispersion strengthening. In addition, the Al—Zr-based intermetallic compound acts on the coarsening of crystal grains during heating. When the addition amount exceeds 0.3%, it becomes easy to form a coarse intermetallic compound, and the plastic workability is lowered. Therefore, the amount of Zr added is set to 0.3% or less. A preferable Zr addition amount is 0.05% to 0.3%.

1-8. Regarding the fourth selective additive element In the aluminum alloy material according to the present invention, in order to further improve the bondability by improving the characteristics of the liquid phase, the essential elements and the first to third selective additive elements are added. In addition to at least one, one or more selected from a predetermined amount of Be, Sr, Bi, Na, and Ca may be further added as the fourth selective additive element. Even when such a fourth selective additive element is contained, the volume density of the Al-based intermetallic compound and the surface density of the Si-based intermetallic compound are defined as described above.

Examples of such elements include Be: 0.1% or less, Sr: 0.1% or less, Bi: 0.1% or less, Na: 0.1% or less, and Ca: 0.05% or less. Two or more kinds are added as necessary. The preferred ranges of these elements are Be: 0.0001% to 0.1%, Sr: 0.0001% to 0.1%, Bi: 0.0001% to 0.1%, Na: 0.0. 0001% to 0.1% or less, Ca: 0.0001% to 0.05% or less. These trace elements can improve the bondability by fine dispersion of Si particles, improvement in fluidity of the liquid phase, and the like. If these trace elements are less than the above-mentioned preferable specified range, effects such as fine dispersion of Si particles and improvement of fluidity of the liquid phase may be insufficient. On the other hand, when the above preferred range is exceeded, adverse effects such as a decrease in corrosion resistance occur.

1-9. Relationship between Si, Fe and Mn Content By the way, both Fe and Mn form an Al—Fe—Mn—Si based intermetallic compound together with Si. Since Si that forms an Al—Fe—Mn—Si-based intermetallic compound has a small contribution to the formation of the liquid phase, the bondability is lowered. Therefore, when adding Fe and Mn in the aluminum alloy material according to the present invention, it is preferable to pay attention to the contents of Si, Fe, and Mn. Specifically, when the contents (mass%) of Si, Fe, and Mn are S, F, and M, respectively, the relational expression of 1.2 ≦ S−0.3 (F + M) ≦ 3.5 is satisfied. Is preferred. When S-0.3 (F + M) is less than 1.2, bonding is insufficient. On the other hand, when S-0.3 (F + M) is larger than 3.5, the shape is likely to change before and after joining.

1-10. Regarding Solid Phase Line and Liquid Phase Line of Materials In addition, the aluminum alloy material that generates the liquid phase of the present invention preferably has a difference between the solid phase temperature and the liquidus temperature of 10 ° C. or more. When the solidus temperature is exceeded, liquid phase generation begins, but if the difference between the solidus temperature and the liquidus temperature is small, the temperature range in which the solid and liquid coexist is narrowed, and the amount of liquid phase generated is controlled. Difficult to do. Therefore, this difference is preferably set to 10 ° C. or more. For example, alloys having a composition satisfying this condition include Al—Si alloys, Al—Si—Mg alloys, Al—Si—Cu alloys, Al—Si—Zn alloys, and Al—Si—Cu—Mg alloys. Can be mentioned. In addition, it becomes easy to control to an appropriate liquid phase amount, so that the difference of solidus temperature and liquidus temperature becomes large. Therefore, the upper limit of the difference between the solidus temperature and the liquidus temperature is not particularly limited.

1-11. Tensile strength before joining by MONOBRAZE method The aluminum alloy material according to the present invention preferably has a tensile strength before joining by MONOBRAZE method of 80 to 250 MPa. If the tensile strength is less than 80 MPa, the strength required for molding into a product shape is insufficient, and molding cannot be performed. If this tensile strength exceeds 250 MPa, the shape retention after molding is poor, and when assembled as a joined body, a gap is formed between the other members and the jointability deteriorates. The tensile strength before bonding by the MONOBRAZE method is a value measured at room temperature of 20 to 30 ° C. Further, the ratio (T / T0) of the tensile strength (T0) before joining by the MONOBRAZE method to the tensile strength (T) after joining is preferably in the range of 0.6 to 1.1. If (T / T0) is less than 0.6, the strength of the material may be insufficient, and the function as a structure may be impaired. If it exceeds 1.1, precipitation at the grain boundary becomes excessive, and the grain boundary Corrosion may occur easily.

2. Next, a method for producing an aluminum alloy material having a heat bonding function with a single layer according to the present invention will be described. The aluminum alloy material according to the present invention is manufactured using a continuous casting method. In the continuous casting method, since the cooling rate at the time of solidification is high, coarse crystals are hardly formed, and formation of Si-based intermetallic compounds having an equivalent circle diameter of 5.0 μm to 10 μm is suppressed. As a result, since the number of recrystallization nuclei can be reduced, only specific crystal grains grow and coarse crystal grains are obtained. In addition, since the solid solution amount of Mn, Fe, and the like is increased, the formation of an Al-based intermetallic compound having a circle-equivalent diameter of 0.01 μm to 0.5 μm is promoted in subsequent processing steps. Thus, by forming an Al-based intermetallic compound having an equivalent circle diameter of 0.01 μm to 0.5 μm, which has the effect of pinning with an appropriate strength and the effect of collecting solute Si in the grains, Only the produced crystal grains grow, coarse crystal grains are obtained, and the formation of a liquid phase at the grain boundary is suppressed, so that the deformation resistance is improved.

In the continuous casting method, the amount of solid solution Si in the matrix decreases due to the formation of an Al-based intermetallic compound having an equivalent circle diameter of 0.01 μm to 0.5 μm. As a result, the amount of solute Si supplied to the grain boundary during bonding heating is further reduced, generation of a liquid phase at the grain boundary is suppressed, and deformation resistance is improved.

The continuous casting method is not particularly limited as long as it is a method of continuously casting a plate-shaped ingot such as a twin roll type continuous casting and rolling method or a twin belt type continuous casting method. The twin-roll type continuous casting and rolling method is a method in which molten aluminum is supplied between a pair of water-cooled rolls from a refractory hot-water supply nozzle, and a thin plate is continuously cast and rolled. The Hunter method, the 3C method, and the like are known. ing. In addition, the twin belt type continuous casting method is a method in which molten metal is poured between rotating belts facing each other up and down and solidified by cooling from the belt surface to form a slab. This is a continuous casting method in which a slab is continuously drawn out and wound into a coil.

In the twin roll type continuous casting and rolling method, the cooling rate during casting is several to several hundred times faster than the semi-continuous casting method. For example, the cooling rate in the semi-continuous casting method is 0.5 to 20 ° C./second, while the cooling rate in the twin roll type continuous casting and rolling method is 100 to 1000 ° C./second. For this reason, the dispersed particles generated during casting have a feature that they are finely and densely distributed as compared with the semi-continuous casting method. As a result, the generation of coarse crystals is suppressed, and the crystal grains during bonding heating become coarse. In addition, since the cooling rate is high, the amount of solid solution of the additive element can be increased. Thereby, a fine precipitate is formed by the subsequent heat treatment, which can contribute to the coarsening of the crystal grains during bonding heating. In the present invention, the cooling rate in the twin roll continuous casting and rolling method is preferably 100 to 1000 ° C./second. If it is less than 100 ° C./second, it is difficult to obtain a target metal structure, and if it exceeds 1000 ° C./second, stable production becomes difficult.

The speed of the rolled plate when casting by the twin roll type continuous casting and rolling method is preferably 0.5 to 3 m / min. The casting speed affects the cooling rate. When the casting speed is less than 0.5 m / min, a sufficient cooling rate as described above cannot be obtained and the compound becomes coarse. On the other hand, when it exceeds 3 m / min, the aluminum material is not sufficiently solidified between rolls during casting, and a normal plate-shaped ingot cannot be obtained.

The molten metal temperature when casting by the twin roll type continuous casting and rolling method is preferably in the range of 650 to 800 ° C. The molten metal temperature is the temperature of the head box immediately before the hot water supply nozzle. When the molten metal temperature is lower than 650 ° C., coarse intermetallic compound dispersed particles are generated in the hot water supply nozzle, and they are mixed into the ingot to cause a sheet break during cold rolling. When the molten metal temperature exceeds 800 ° C., the aluminum material is not sufficiently solidified between the rolls during casting, and a normal plate-shaped ingot cannot be obtained. A more preferable molten metal temperature is 680 to 750 ° C.

The plate thickness of the plate-shaped ingot cast by the twin roll continuous casting and rolling method is preferably 2 mm to 10 mm. In this thickness range, the solidification rate at the central portion of the plate thickness is fast, and a uniform structure can be easily obtained. When the plate thickness is less than 2 mm, the amount of aluminum passing through the casting machine per unit time is small, and it becomes difficult to stably supply the molten metal in the plate width direction. On the other hand, if the plate thickness exceeds 10 mm, winding with a roll becomes difficult. A more preferable plate thickness of the plate-shaped ingot is 4 mm to 8 mm.

In the process of cold rolling the plate-shaped ingot cast by the twin roll continuous casting and rolling method to the final plate thickness, annealing is performed at 250 to 550 ° C. for 1 to 10 hours. This annealing may be performed in any process except the final cold rolling in the manufacturing process after casting, and it is necessary to perform it once or more. In addition, the upper limit of the number of times of annealing is preferably 3 times, more preferably 2 times. This annealing is performed in order to soften the material and make it easy to obtain the desired material strength by final rolling. By this annealing, the size and density of the intermetallic compound in the material and the solid solution amount of the additive element are optimally adjusted. I can do it. When the annealing temperature is less than 250 ° C., the softening of the material is insufficient, and the TS before brazing heating becomes high. When TS before brazing heating is high, since the moldability is inferior, the core dimensions are deteriorated, and as a result, the durability is lowered. On the other hand, if annealing is performed at a temperature exceeding 550 ° C., the amount of heat input to the material during the manufacturing process becomes too large, so that the intermetallic compounds are coarsely and sparsely distributed. Coarse and loosely distributed intermetallic compounds are difficult to incorporate solid solution elements, and the amount of solid solution in the material is difficult to decrease. Further, the above effect is not sufficient at an annealing temperature of less than 1 hour, and the above effect is saturated at an annealing time exceeding 10 hours, which is economically disadvantageous.

Also, the tempering may be O material or H material. When the H1n material or the H2n material is used, the final cold rolling rate is important. The final cold rolling rate is 50% or less, and the preferable final cold rolling rate is 5% to 50%. When the final cold rolling rate exceeds 50%, a large number of recrystallization nuclei are generated during heating, and the crystal grain size after bonding heating becomes fine. In addition, if the final cold rolling reduction is less than 5%, the manufacture may be substantially difficult.

2-1. Control of Intermetallic Compound Density in Twin Roll Continuous Casting and Rolling Process The dispersed particles can be made finer than in semi-continuous casting by the above-described twin roll continuous casting and rolling process and the subsequent manufacturing process. However, in order to obtain the metal structure of the aluminum alloy material according to the present invention, it is important to control the cooling rate during solidification more precisely. The inventors of the present invention have found that the cooling rate can be controlled by controlling the thickness of the aluminum coating and by controlling the sump in the melt by the rolling load.

2-1-1. Control of aluminum coating thickness Aluminum coating is a film composed mainly of aluminum and aluminum oxide. The aluminum coating formed on the roll surface during casting improves the wetting between the roll surface and the molten metal and improves the heat transfer between the roll surface and the molten metal. In order to form an aluminum coating, twin roll continuous casting and rolling may be performed with a molten aluminum of 680 to 740 ° C. at a rolling load of 500 N / mm or more, or before the start of twin roll continuous casting and rolling. The wrought aluminum alloy sheet heated to 300 ° C. or higher may be rolled twice or more at a rolling reduction of 20% or more. The molten aluminum or aluminum alloy plate used for forming the aluminum coating is particularly preferably a 1000 series alloy with few additive elements, but the coating can be formed using other aluminum alloy systems. During casting, the thickness of the aluminum coating always increases, so boron nitride or carbon release agent (graphite spray or soot) is applied to the roll surface at 10 μg / cm ² to suppress further formation of the aluminum coating. It can also be physically removed with a brush roll or the like.

The aluminum coating thickness is preferably 1 to 500 μm. Thereby, the cooling rate of the molten metal is optimally adjusted, and it becomes possible to cast an aluminum alloy having an intermetallic compound density and an Si solid solution amount that are excellent in deformation resistance during bonding heating. If the aluminum coating thickness is less than 1 μm, the wettability between the roll surface and the molten metal is poor, and the contact area between the roll surface and the molten metal becomes small. Thereby, the heat transferability between the roll surface and the molten metal deteriorates, and the cooling rate of the molten metal decreases. As a result, the intermetallic compound becomes coarse and a desired intermetallic compound density cannot be obtained. Further, when the wettability between the roll surface and the molten metal is poor, the roll surface and the molten metal may be locally non-contact. In that case, the ingot is remelted and the molten metal having a high solute concentration oozes out to the surface of the ingot to cause surface segregation, and there is a possibility that a coarse intermetallic compound is formed on the surface of the ingot. On the other hand, when the aluminum coating thickness exceeds 500 μm, the wettability between the roll surface and the molten metal is improved, but the heat transferability between the roll surface and the molten metal is significantly deteriorated because the coating is too thick. As a result, the cooling rate of the molten metal also decreases in this case, so that the intermetallic compound becomes coarse, and the desired intermetallic compound density and Si solid solution amount cannot be obtained. The aluminum coating thickness is more preferably 80 to 410 μm.

2-1-2. Control of molten sump by rolling load It is desirable to control the intermetallic compound density of the continuous cast plate by controlling the cooling rate during solidification. However, it is very difficult to measure the cooling rate during casting, and it is necessary to control the intermetallic compound density with parameters that can be measured online.

In the twin roll type continuous casting and rolling method, as shown in FIGS. 1 and 2, in the region 2 surrounded by the metal cooling rolls 2 </ b> A and 2 </ b> B, the roll center line 3, and the outlet of the nozzle tip 4, which are opposed to each other vertically. It is carried out by injecting a molten aluminum alloy 1 through a nozzle tip 4 made of refractory. Here, the region 2 during continuous casting can be roughly divided into a rolled region 5 and a non-rolled region 6. The aluminum alloy in the rolling region 5 has been solidified to become an ingot, and a roll separating force is generated against the rolling of the roll. On the other hand, although the aluminum alloy in the non-rolled region 6 has been solidified in the vicinity of the roll, the center portion of the plate thickness exists as an unsolidified molten metal, so that no roll separation force is generated. The position of the solidification start point 7 hardly moves even if the casting conditions are changed. Therefore, if the casting speed is increased or the molten metal temperature is increased and the rolling region 5 is reduced as shown in FIG. 1, the molten sump is deepened, and as a result, the cooling rate is decreased. Conversely, when the casting speed is slowed or the molten metal temperature is lowered and the rolling region 5 is enlarged as shown in FIG. 2, the molten sump becomes shallower and the cooling rate increases. Thus, the cooling rate can be controlled by measuring the rolling load 8, which is the vertical component of the roll separation force, that is, the increase / decrease of the rolling region. In addition, the molten metal sump is a solid-liquid interface between the solidified part and the unsolidified part at the time of casting, and when this interface deeply penetrates in the rolling direction to form a valley shape, the sump is deep, On the other hand, if the interface is nearly flat without entering the rolling direction, the sump is shallow.

The rolling load is preferably 500 to 5000 N / mm. When the rolling load is less than 500 N / mm, as shown in FIG. 1, the rolling region 4 is small and the melt sump is deep. Thereby, a cooling rate becomes low, a coarse crystallized substance is easy to be formed, and it becomes difficult to form a fine precipitate. As a result, the number of recrystallized grains having coarse crystallized crystals as nuclei increases during bonding heating, and the crystal grains become finer, so that they are easily deformed. In addition, due to the sparseness of fine precipitates, an appropriate pinning effect cannot be obtained, and the amount of Si solid solution increases, so that the liquid phase generated at the grain boundary during bonding heating increases and is likely to deform. . In addition, solute atoms gather at the center of the plate thickness and cause centerline segregation.

On the other hand, when the rolling load exceeds 5000 N / mm, as shown in FIG. 2, the rolling region 5 is large and the molten sump is shallow. As a result, the cooling rate becomes too high, and the Al-based intermetallic compound distribution becomes overcrowded. As a result, the pinning effect is excessively exerted during the heating of the bonding, so that the crystal grains become fine and easily deform. Further, since the amount of heat removed from the roll surface is large, solidification proceeds to the molten metal (meniscus portion 9) that is not in contact with the roll surface. Therefore, the molten metal supply during casting becomes insufficient, the ripple becomes deep, and surface defects on the ingot surface occur. This surface defect can be a starting point for cracking during rolling.

2-2. Measuring Method of Rolling Load In the twin roll type continuous casting rolling method, a force that the ingot pushes up the roll during casting and a constant force that is applied between the upper and lower rolls from before casting to during casting are generated. The sum of these two forces can be measured by a hydraulic cylinder as a component parallel to the roll center line. Therefore, the rolling load is obtained by converting the increase in cylinder pressure before the start of casting and during casting into force and dividing by the width of the cast plate. For example, when the number of cylinders is 2, the cylinder diameter is 600 mm, the increase of one cylinder pressure is 4 MPa, and the width of the rolled plate during casting is 1500 mm, the rolling load per unit width of the plate-shaped ingot is as follows: From the equation, 1508 N / mm.
4 × 300 ² × π ÷ 1500 × 2 = 1508 N / mm

3. Next, an aluminum joined body according to the present invention will be described. In the present invention, an aluminum joined body is manufactured using the MONOBRAZE method that utilizes the joining ability exhibited by the aluminum alloy material itself without using a brazing material. In the present invention, the aluminum joined body is a joined body in which two or more members are joined, and at least one member constituting the joined body is made of the aluminum alloy material according to the present invention. The other member may be an aluminum alloy material according to the present invention, or another aluminum alloy material or a pure aluminum material. The method for producing an aluminum joined body according to the present invention comprises combining the aluminum alloy material according to the present invention with at least one member to be joined as another member to be joined with another member to be joined, followed by heat treatment. A joining member is joined. For example, considering the use of a heat exchanger as a fin material, deformation of the fin material itself becomes a major issue. Therefore, it is important to manage the bonding conditions of the MONOBRAZE method. Specifically, it is not lower than the solidus temperature at which the liquid phase is generated in the aluminum alloy material according to the present invention and not higher than the liquidus temperature, and the liquid phase is generated in the aluminum alloy material, resulting in a reduced strength and shape. Heating is performed for a time required for bonding at a temperature equal to or lower than the temperature at which it is impossible to maintain the temperature.

As more specific heating conditions, the ratio of the mass of the liquid phase generated in the aluminum alloy material to the total mass of the aluminum alloy material (hereinafter referred to as the liquid phase ratio) exceeds 0% and is 35% or less. It is necessary to join at temperature. Since the bonding cannot be performed unless the liquid phase is generated, the liquid phase ratio needs to be more than 0%. However, if the liquid phase is small, joining may be difficult, so the liquid phase ratio is preferably 5% or more. If the liquid phase ratio exceeds 35%, the amount of liquid phase to be generated is too large, and the aluminum alloy material is greatly deformed during bonding heating, and the shape cannot be maintained. A more preferable liquid phase ratio is 5 to 30%, and a still more preferable liquid phase ratio is 10 to 20%.

Further, in order to sufficiently fill the liquid phase between the members to be joined, it is preferable to consider the filling time, and the time during which the liquid phase ratio is 5% or more is preferably 30 to 3600 seconds. More preferably, the time during which the liquid phase ratio is 5% or more is 60 to 1800 seconds, whereby sufficient filling is performed and reliable bonding is performed. If the time during which the liquid phase ratio is 5% or more is less than 30 seconds, the joint may not be sufficiently filled with the liquid phase. On the other hand, if it exceeds 3600 seconds, the deformation of the aluminum material may proceed. In the bonding method according to the present invention, the liquid phase moves only in the very vicinity of the bonded portion, so that the time required for filling does not depend on the size of the bonded portion.

As a specific example of desirable heating conditions, in the case of the aluminum alloy material according to the present invention, the bonding temperature may be 580 ° C. to 640 ° C., and the holding time at the bonding temperature may be about 0 to 10 minutes. Here, 0 minutes means that the cooling is started as soon as the temperature of the member reaches a predetermined joining temperature. The holding time is more preferably 30 seconds to 5 minutes. Regarding the bonding temperature, for example, when the Si amount is about 1 to 1.5%, it is desirable to increase the bonding heating temperature to 610 to 640 ° C. Conversely, when the Si amount is about 4 to 5%, the bonding heating temperature may be set to a low value of 580 to 590 ° C. Moreover, you may adjust a heating condition according to a composition in order to make the metal structure of a junction part into the suitable state mentioned later.

Note that it is extremely difficult to measure the actual liquid phase rate during heating. Therefore, the liquid phase ratio defined in the present invention can be usually obtained by lever principle from the alloy composition and the maximum attainable temperature using an equilibrium diagram. In an alloy system whose phase diagram is already known, the phase diagram can be used to determine the liquid phase ratio using the principle of leverage. On the other hand, for an alloy system whose equilibrium diagram is not disclosed, the liquid phase ratio can be obtained using equilibrium calculation diagram software. The equilibrium calculation phase diagram software incorporates a technique for determining the liquid phase ratio based on the lever principle using the alloy composition and temperature. Equilibrium calculation state diagram software includes Thermo-Calc; Thermo-Calc Software AB, etc. Even in an alloy system whose equilibrium phase diagram has been clarified, calculating the liquid phase rate using the equilibrium calculation phase diagram software is the same as the result of calculating the liquid phase rate using this principle from the equilibrium phase diagram. As a result, equilibrium calculation state diagram software may be used for simplification.

Further, the heating atmosphere in the heat treatment is preferably a non-oxidizing atmosphere substituted with nitrogen, argon or the like. In addition, better bondability can be obtained by using a non-corrosive flux. Furthermore, it is also possible to join by heating in vacuum or reduced pressure.

Examples of the non-corrosive flux coating method include a method of sprinkling the flux powder after assembling the members to be joined, and a method of spraying the flux powder suspended in water. When the material is coated in advance, the adhesion of the coating can be improved by mixing and applying a binder such as an acrylic resin to the flux powder. Examples of the non-corrosive flux used for obtaining a normal flux function include KAlF ₄ , K ₂ AlF ₅ , K ₂ AlF ₅ .H ₂ O, K ₃ AlF ₆ , AlF ₃ , KZnF ₃ , K ₂ SiF _{6 and the} like. And cesium-based fluxes such as Cs ₃ AlF ₆ , CsAlF ₄ .2H ₂ O, Cs ₂ AlF ₅ .H ₂ O, and the like.

The aluminum alloy material having a heat bonding function with a single layer according to the present invention can be bonded well by the above heat treatment and control of the heating atmosphere. However, particularly when the liquid phase ratio at the time of bonding is increased, the stress generated in the aluminum alloy material can be maintained at a relatively small stress so that a good shape can be maintained. When it is preferable to consider the stress in the aluminum alloy material in this way, when the maximum value of the stress generated in the aluminum alloy material is P (kPa) and the liquid phase ratio is V (%), P If the condition of ≦ 460-12V is satisfied, a very stable junction can be obtained. The value indicated by the right side (460-12V) of this equation is the critical stress, and if a stress exceeding this value is applied to the aluminum alloy material, there is a risk of significant deformation. The stress generated in the aluminum alloy material is determined from the shape and load. For example, it can be calculated using a structural calculation program or the like.

Furthermore, the surface form of the joint as well as the pressure of the joint may affect the bondability, and a smoother surface can be obtained when both surfaces are smooth. In the present invention, when the sum of the arithmetic average waviness Wa1 and Wa2 obtained from the unevenness of the surfaces of both joint surfaces of the paired members to be joined before joining satisfies Wa1 + Wa2 ≦ 10 (μm), it is more sufficient. Bonding is obtained. The arithmetic mean waviness Wa1 and Wa2 are defined by JISB0633, and the cut-off value is set so that the wavelength becomes uneven between 25 and 2500 μm, and the waviness curve measured with a laser microscope or a confocal microscope. It is requested from.

4). About the crystal grain size in the metallographic structure of the aluminum alloy material after heat bonding The aluminum alloy material having a heat bonding function with a single layer according to the present invention preferably has a crystal particle size of 100 μm or more after heat bonding by the MONOBRAZE method. . Since the grain boundary portion is melted at the time of heating, if the crystal grains are small, the crystal grains are liable to be displaced at the grain boundary, causing deformation. Since observation of crystal grains during heating is extremely difficult, the crystal grain diameter after heating is judged. When the crystal grains after heating are less than 100 μm, the material is likely to be deformed during bonding. The upper limit of the crystal grain size is not particularly limited, but depends on the manufacturing conditions of the aluminum alloy material and the bonding conditions of the MONOBRAZE method, and is 1500 μm in the present invention. The measurement of crystal grains is calculated as the average crystal grain diameter based on the crystal grain measurement method of ASTM E112-96.

Hereinafter, the present invention will be described in detail based on examples and comparative examples.

First Embodiment: First, test materials having components A1 to A67 in Tables 1 to 3 were used. In these tables, “−” in the alloy composition indicates that it is below the detection limit, and “remainder” includes inevitable impurities. A cast ingot was produced by the twin roll continuous casting and rolling method (CC) using the test material. The melt temperature at the time of casting by the twin roll type continuous casting and rolling method was 650 to 800 ° C., and the casting speed was variously changed as shown in Tables 4 to 6. Although it is difficult to directly measure the cooling rate, as described above, the cooling rate is in the range of 300 to 700 ° C./second by controlling the aluminum coating thickness and controlling the sump in the molten metal by rolling load. it is conceivable that. By such a casting process, a cast ingot having a width of 130 mm, a length of 20000 mm, and a thickness of 7 mm was obtained. Next, the obtained plate-shaped ingot is cold-rolled to 0.7 mm, after intermediate annealing at 420 ° C. × 2 hours, cold-rolled to 0.071 mm, and then annealed at 350 ° C. × 3 hours for the second time. Later, it was rolled to 0.050 mm at a final cold rolling rate of 30% to obtain a test material. The arithmetic average waviness Wa of the test material was about 0.5 μm.

During casting, a crystal grain refining agent was added at a molten metal temperature of 680 ° C to 750 ° C. At that time, the molten metal flowing through the tub connecting between the molten metal holding furnace and the head box just before the hot water supply nozzle was continuously charged at a constant speed using a wire-shaped crystal grain refining agent rod. As the crystal grain refining agent, an Al-5Ti-1B alloy was used, and the addition amount was adjusted to be 0.002% in terms of B amount.

Moreover, the test materials of the components A44, 48, 50, 51, and 54 in Tables 2 and 3 were cast in a size of 100 mm × 300 mm using a semi-continuous casting method (DC). The casting rate was 30 mm / min, and the cooling rate was 1 ° C./second. The ingot cast by the semi-continuous casting method was hot-rolled to 3 mm by heating to 500 ° C. after chamfering. Thereafter, the rolled plate was cold-rolled to 0.070 mm, subjected to intermediate annealing at 380 ° C. for 2 hours, and further rolled to 0.050 mm at a final cold rolling rate of 30% to obtain a test material.

These test materials were evaluated for manufacturability in the production process. The evaluation method for manufacturability is as follows: when a plate or slab is manufactured, no problem occurs in the manufacturing process and a sound plate or slab is obtained. The case where rolling became difficult due to the generation of a huge intermetallic compound and there was a problem in manufacturability was evaluated as x.

Moreover, the volume density of the Al-based intermetallic compound in the manufactured plate material (element plate) was measured by TEM observation of a cross section along the plate thickness direction. A sample for TEM observation was prepared using electrolytic etching. During TEM observation, the film thickness was determined by EELS measurement, and a field of view having an average film thickness of 50 to 200 μm was selected and observed. The Si-based intermetallic compound and the Al-based intermetallic compound can be distinguished by performing mapping by STEM-EDS. Observation was performed for 10 fields of view at 100000 times for each sample, and the number of Al-based intermetallic compounds having an equivalent circle diameter of 0.01 μm to 0.5 μm was measured by image analysis of each TEM photograph. The measurement area of this image was multiplied by the average film thickness to obtain the measurement volume, and the volume density was calculated.

Further, the surface density of the Si-based intermetallic compound in the produced plate material (element plate) was measured by SEM observation of a cross section along the plate thickness direction. Si-based intermetallic compounds and Al-based intermetallic compounds (Al-Fe-Mn-Si-based intermetallic compounds) were distinguished using SEM-backscattered electron image observation and SEM-secondary electron image observation. In the backscattered electron image observation, an Al-based intermetallic compound provides a strong white contrast, and an Si-based intermetallic compound provides a low white contrast. Since the Si-based intermetallic compound has a weak contrast, it may be difficult to distinguish fine particles. In this case, a sample etched for about 10 seconds with a colloidal silica suspension after surface polishing was observed with a SEM-secondary electron image. Particles that provide a strong black contrast are Si-based intermetallic compounds. Observation was carried out for 5 fields of each sample, and the SEM photograph of each field of view was subjected to image analysis to examine the surface density of the Si-based intermetallic compound having a circle-equivalent diameter of 5.0 μm to 10 μm.

Next, as shown in FIG. 3, each test material was formed into a fin material having a width of 16 mm, a mountain height of 7 mm, and a pitch of 2.5 mm. The combination material of composition B1 in Table 3 was combined with a 0.4 mm thick electro-sealed tube material and incorporated in a stainless steel jig to produce a three-stage test piece (minicore) shown in FIG. .

This mini-core is immersed in a 10% suspension of non-corrosive fluoride flux, dried, and then heated in a nitrogen atmosphere under the joining heating conditions shown in Tables 4 to 6 to join the fin material and the tube material. did. In addition, about Example 16, it heated and joined in the vacuum, without apply | coating a flux. Also, the holding time at each temperature during bonding was set to 30 to 3600 seconds. In the case of this mini-core, a compressive load of about 4N is generated between the stainless steel jig and the mini-core due to the difference in thermal expansion coefficient between the stainless steel jig and the aluminum material. A stress of about 10 kPa is generated on the surface.

After joining the fin material and the tube material, the fin was peeled from the tube, and the 40 joint portions of the mini-core tube and the fin were examined, and the ratio (joining rate) of the completely joined portions was measured. Then, the joining rate was judged as ◎ for 90% or more, ○ for 80% or more and less than 90%, Δ for 70% or more and less than 80%, and × for less than 70%.

Also, the fin height of the mini-core before and after joining was measured to evaluate the deformation rate due to fin buckling. That is, the ratio of the fin height change (decrease) after bonding to the fin height before bonding is 3% or less, ◎ 3% to 5% or less, ◯ 5% to 8% or less, △, 8% Those exceeding the value were judged as x.

In this embodiment, the tensile test of the material before and after joining by the MONOBRAZE method was performed. The tensile test was performed on each sample at a room temperature of 20 to 30 ° C. according to JIS Z2241 under the conditions of a tensile speed of 10 mm / min and a gauge length of 50 mm. In addition, the tensile test after joining by MONOBRAZE method evaluated the sample heated on the joining heating conditions of MONOBRAZE method equivalent to a mini-core within 24 hours after cooling to the said room temperature.

In this embodiment, the crystal grain size in the metal structure of the material after bonding by the MONOBRAZE method was measured. The measurement method was a method based on ASTM E112-96. First, after heating the veneer of the sample of the present invention under the bonding heating condition equivalent to that of the mini-core, the L-LT cross section was polished and surface-treated by anodizing to facilitate observation of the crystal grain structure. The crystal grain structure of the sample of the present invention is observed with an optical microscope, and the reference image of the crystal grain structure defined by ASTM is compared with the cross-sectional image of the sample of the present invention. The crystal grain size of the reference image with similar is adopted.

For each of the above test materials, casting method, casting speed, manufacturability evaluation, volume density of Al-based intermetallic compound, surface density of Si-based intermetallic compound, bonding heating condition, tensile test evaluation before and after bonding, crystal after bonding Tables 4 to 6 show the particle size, bonding rate, and deformation rate. Note that the equilibrium liquid phase ratio under the bonding heating condition is a value calculated by equilibrium phase diagram calculation software.

From Tables 4 and 5, those having the conditions specified by the present invention in the composition of the aluminum alloy material had good manufacturability. On the other hand, as shown in Table 6, in the processing of the alloy compositions A55 and A60 to A64, the alloy composition was not within the specified range, so that a huge intermetallic compound was formed during casting, and it was not possible to roll to the final plate thickness.

Next, with regard to the bonding test results, the evaluation results for each sample of the mini-core and the composition of the aluminum alloy material of the fin material (Tables 1 to 3) are compared. The test materials (Examples 1 to 40) having the conditions defined by the present invention with respect to the composition of the aluminum alloy material passed all of the joining rate, fin buckling, and tensile strength. Examples 12 to 26 are test materials made of an alloy to which Mg, Cu, Mn, Ni, Ti, V, Zr, and Cr are further added as additive elements. It was confirmed that these additive elements had an effect of improving the strength.

On the other hand, in Comparative Example 1, since the Si component was less than the specified amount, even when the bonding heating temperature was relatively high, the liquid phase generation rate was low, the bonding rate was low, and the bonding property was unacceptable.

In Comparative Example 2, since the Si component exceeded the specified amount, the liquid phase generation rate was high even when the bonding heating temperature was relatively low, the fins buckled, and the deformation rate was unacceptable.

In Comparative Example 3, each component of Si, Fe, and Mn is within the specified amount range, but the volume density of the Al-based intermetallic compound is less than specified, the crystal grains after heating become smaller, and the liquid phase formation Since the number of nuclei was small, the formation of a liquid phase at the grain boundary was promoted, the fins buckled, and the deformation rate was unacceptable.

In Comparative Example 4, since both Fe and Mn components exceeded the specified amount, there was a problem in manufacturability and evaluation could not be performed.

In Comparative Example 5, since the Fe component is less than the prescribed amount, the volume density of the Al-based intermetallic compound is less than the prescribed density, the crystal grain size after heating is small, and the number of nuclei for liquid phase formation is small. Formation of the liquid phase at the boundary was promoted, the fins buckled, and the deformation rate was unacceptable.

In Comparative Example 6, the Si, Fe, and Mn components are all within the specified amount range, but the volume density of the Al-based intermetallic compound exceeds the specified value, and the number of nuclei for forming the liquid phase is too large, so that it contacts the grain boundary. The liquid phase increased, the fins buckled and the deformation rate was unacceptable.

In Comparative Example 7, the Si and Fe components are both within the specified amount range, but the volume density of the Al-based intermetallic compound is lower than the specified density, the crystal grain size after heating is reduced, and the liquid phase is formed. Since the number of nuclei was small, the formation of a liquid phase at the grain boundary was promoted, the fins buckled, and the deformation rate was unacceptable.

In Comparative Example 8, the Si and Fe components are both within the specified amount range, but the surface density of the Si-based intermetallic compound exceeds the specified value, and the volume density of the Al-based intermetallic compound is lower than the specified value. Since the crystal grains were small and there were few nuclei for liquid phase formation, liquid phase formation at the grain boundaries was promoted, the fins buckled, and the deformation rate was unacceptable.

In Comparative Example 9, since the Mg content exceeded the specified value, the flux did not work effectively during the heating of the joint, the joining performance was lowered, and the evaluation of the joining rate was unacceptable.

In Comparative Example 10, since the Ni content exceeded the regulation, there was a problem in manufacturability and the evaluation could not be performed.

In Comparative Example 11, since the Ti content exceeded the regulation, there was a problem in manufacturability and the evaluation could not be performed.

In Comparative Example 12, since the V content exceeded the regulation, there was a problem in manufacturability, and evaluation could not be performed.

In Comparative Example 13, since the content of Zr exceeded the regulation, there was a problem in manufacturability and the evaluation could not be performed.

In Comparative Example 14, since the Cr content exceeded the regulation, there was a problem in manufacturability and evaluation could not be performed.

Second Embodiment: Here, the effect of additive elements on corrosion resistance was examined. As shown in Table 7, the material manufactured in the first embodiment was extracted and formed into the same fin as in the first embodiment. And the test piece (mini-core) of 3 steps | paragraphs was produced similarly to 1st Embodiment (FIG. 3). This mini-core is immersed in a 10% suspension of non-corrosive fluoride flux, dried, then heated to various bonding heating temperatures shown in Table 7 in a nitrogen atmosphere, and held for 3 minutes. The fin and the tube were joined.

And the joining rate and the deformation rate were evaluated in the same manner as in the first embodiment. Further, similarly to the first embodiment, the volume density of the Al-based intermetallic compound, the surface density of the Si-based intermetallic compound, and the crystal grain size after bonding heating were also measured. These evaluation results and measurement results are shown in Table 7.

Furthermore, a CASS test was conducted for 500 hours to evaluate the corrosion resistance of the fin itself, and the corrosion state of the fin was confirmed. In the cross-sectional observation with an optical microscope, 70% or more of the fins remained ◎, 50% to less than 70% ○, 30% to less than 50% △, and less than 30% to × did. The above evaluation results are shown in Table 7.

In Examples 41 to 54 in this embodiment, an aluminum alloy to which Zn, Cu, Mn, In, Sn, Ti, and V are added as additive elements is used as a test material. From Table 7, the improvement of corrosion resistance was seen compared with the aluminum alloy in which Zn etc. of Example 41 to which Zn or the like was not added was confirmed, and the usefulness of these additive elements could be confirmed.

On the other hand, in Comparative Example 15, since the Cu content exceeded the regulation, the self-corrosion resistance was lowered, and the evaluation of the corrosion resistance was rejected.

In Comparative Example 16, since the Zn content exceeded the regulation, the corrosion rate was remarkably increased, and the evaluation of corrosion resistance was rejected.

In Comparative Example 17, since the In content exceeded the specified value, the corrosion rate was remarkably increased and the evaluation of corrosion resistance was rejected.

In Comparative Example 18, since the Sn content exceeded the regulation, the corrosion rate was remarkably increased, and the evaluation of corrosion resistance was rejected.

Third Embodiment: Here, the control of the metal structure by the manufacturing process was examined. From the material manufactured in the first embodiment, the composition No. A3 was extracted and fin materials with a final plate thickness of 0.05 mm were manufactured in various manufacturing steps as shown in Table 8. The surface density of the Si-based intermetallic compound, the surface density of the Al-based intermetallic compound, and the Si solid solution amount of the base plate of each material were measured. The results are shown in Table 9. In this embodiment, the surface density of the Si intermetallic compound having an equivalent circle diameter of less than 5 μm and exceeding 10 μm and the volume density of the Al intermetallic compound having an equivalent circle diameter of more than 0.5 μm were also measured. The results are also shown in Table 9.

Next, the same fin as in the first embodiment was formed. And the test piece (mini-core) of 3 steps | paragraphs was produced similarly to 1st Embodiment (FIG. 3). This mini-core is immersed in a 10% suspension of non-corrosive fluoride flux, dried, and then heated to 600 ° C. in a nitrogen atmosphere.
The fin and the tube were joined while maintaining the holding time of 3 minutes. The measurement of the crystal grain size after bonding heating and the evaluation of bonding property and deformability were performed in the same manner as in the first embodiment. The results are shown in Table 9.

As shown in Tables 8 and 9, since the manufacturing process was appropriate in Examples 55 to 68, the Si-based intermetallic compound density, the Al-based intermetallic compound density, and the Si solid solution amount specified in the present invention in the final plate were as follows. As a result, the joining rate and deformation rate met the standards and passed.

In Comparative Example 19, since the rolling load during casting was too small, the cooling rate was slow, the surface density of the Si-based intermetallic compound having an equivalent circle diameter of 5 to 10 μm exceeded the specified value in the final plate, and the crystal grain size after heating was It became small and the evaluation of the deformation rate was unacceptable.

In Comparative Example 20, since the rolling load was too large, the molten metal supply was insufficient, cracking occurred during casting, and production was impossible.

In Comparative Example 21, since the roll coating thickness at the time of casting was zero, the cooling rate was slow, and the volume density of the Al-based intermetallic compound having an equivalent circle diameter of 0.01 to 0.5 μm in the final plate was below the specified value. Since the crystal grain size later became smaller and the amount of Si solid solution exceeded the specified value, the deformation rate was rejected.

In Comparative Example 22, since the roll coating thickness at the time of casting was too thick, the cooling rate was slow, and the volume density of the Al-based intermetallic compound having an equivalent circle diameter of 0.01 to 0.5 μm in the final plate was below the specified value. The crystal grain size was small, and the Si solid solution amount exceeded the specified value, so the deformation rate was unacceptable.

In Comparative Example 23, the first annealing temperature was low, the volume density of the Al-based intermetallic compound having an equivalent circle diameter of 0.01 to 0.5 μm exceeded the specification, and the deformation rate was unacceptable.

In Comparative Example 24, the first annealing temperature was high, the volume density of the Al-based intermetallic compound having an equivalent circle diameter of 0.01 to 0.5 μm was less than the specified value, and the Si solid solution amount exceeded the specified value. The deformation rate was unacceptable.

In Comparative Example 25, the first annealing time was short, the volume density of the Al-based intermetallic compound having an equivalent circle diameter of 0.01 to 0.5 μm exceeded the specification, and the deformation rate was unacceptable.

In Comparative Example 26, the first annealing time was long, the volume density of the Al-based intermetallic compound having an equivalent circle diameter of 0.01 to 0.5 μm was less than the specified value, and the Si solid solution amount exceeded the specified value. The deformation rate was unacceptable.

An aluminum alloy material having a heat bonding function with a single layer according to the present invention is particularly useful as a fin material of a heat exchanger, for example, and without using a bonding member such as a brazing material or a filler material. It can be joined to other members, and the heat exchanger can be manufactured efficiently. When the aluminum alloy material according to the present invention is heat-bonded by the MONOBRAZE method, there is almost no change in size or shape. The aluminum alloy material and the joined body using the same according to the present invention have remarkable industrial effects.

DESCRIPTION OF SYMBOLS 1 ... Molten aluminum alloy 2 ... Area | region 2A ... Roll 2B ... Roll 3 ... Roll centerline 3
4 ... Nozzle tip 5 ... Rolling area
6 ... Non-rolling region 7 ... Solidification start point 8 ... Rolling load 9 ... Meniscus part

Claims

Si: 1.0 to 5.0 mass%, Fe: 0.01 to 2.0 mass%, and the balance is made of an aluminum alloy consisting of Al and inevitable impurities, and has an equivalent circle diameter of 0.01 to 0.5 μm. The Al-based intermetallic compound has 10 to 1 × 10 4 pieces / μm 3, and the Si-based intermetallic compound having an equivalent circle diameter of 5.0 to 10 μm exists to 200 pieces / mm 2 or less. Aluminum alloy material that has a single-layer heat bonding function.
The aluminum alloy material having a single layer heat-bonding function according to claim 1, wherein the amount of solute Si contained in the aluminum alloy is 0.7% or less.
The aluminum alloy further contains one or more selected from Mg: 0.05 to 2.0 mass%, Cu: 0.05 to 1.5 mass%, and Mn: 0.05 to 2.0 mass%. An aluminum alloy material having a heat bonding function with a single layer according to claim 1.
The aluminum alloy further contains one or more selected from Zn: 6.0 mass% or less, In: 0.3 mass% or less, and Sn: 0.3 mass% or less. An aluminum alloy material having a heat bonding function with a single layer according to claim 1.
The aluminum alloy is one selected from Ti: 0.3 mass% or less, V: 0.3 mass% or less, Cr: 0.3 mass% or less, Ni: 2.0 mass% or less, and Zr: 0.3 mass% or less The aluminum alloy material having a heat bonding function with a single layer according to any one of claims 1 to 4, further comprising two or more kinds.
The aluminum alloy is selected from Be: 0.1 mass% or less, Sr: 0.1 mass% or less, Bi: 0.1 mass% or less, Na: 0.1 mass% or less, and Ca: 0.05 mass% or less. Alternatively, the aluminum alloy material having a heat bonding function with a single layer according to any one of claims 1 to 5, further comprising two or more kinds.
7. The aluminum alloy material having a single layer heat-bonding function according to any one of claims 1 to 6, wherein the tensile strength before heat-bonding is 80 to 250 MPa.
A method for producing an aluminum alloy material having a heat-bonding function with a single layer according to any one of claims 1 to 7, wherein the aluminum alloy material for the aluminum alloy material is continuously rolled and rolled by a twin roll method. Including two or more cold rolling processes for cold rolling the rolled sheet and an annealing process for annealing the rolled sheet one or more times during the cold rolling process, and the annealing conditions in all annealing processes are 250 to 550 ° C. A method for producing an aluminum alloy material having a single layer heat-bonding function, characterized in that the temperature is 1 to 10 hours at a temperature of 1 to 10 hours, and the rolling reduction in the final cold rolling stage is 50% or less.
In the twin roll type continuous casting and rolling of the casting process, a roll having a thickness of 1 to 500 μm mainly composed of aluminum and aluminum oxide is rolled in a state of adhering to the surface of the twin roll, The method for producing an aluminum alloy material having a single layer heat-bonding function according to claim 8, wherein the rolling load is 500 to 5000 N.
The aluminum alloy material according to any one of claims 1 to 7, wherein the aluminum alloy material is manufactured by heat-bonding two or more aluminum members, and at least one of the two or more aluminum members is used. Aluminum joined body.
The aluminum joined body according to claim 10, wherein a crystal grain size in a metal structure of the aluminum alloy material used for at least one of the two or more members is 100 μm or more after heat joining.